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1.
The reactions of aliphatic and aromatic amines with reducing sugars are important in both drug stability and synthesis. The
formation of glycosylamines in solution, the first step in the Maillard reaction, does not typically cause browning but results
in decreased potency and is hence significant from the aspect of drug instability. The purpose of this research was to present
(1) unreported ionic equilibria of model reactant (kynurenine), (2) the analytical methods used to characterize and measure
reaction products, (3) the kinetic scheme used to measure reaction rates and (4) relevant properties of various reducing sugars
that impact the reaction rate in solution. The methods used to identify the reversible formation of two products from the
reaction of kynurenine and monosaccharides included LC mass spectrometry, UV spectroscopy, and 1-D and 2-D 1H–1H COSY NMR spectroscopy. Kinetics was studied using a stability-indicating HPLC method. The results indicated the formation
of α and β glycosylamines by a pseudo first-order reversible reaction scheme in the pH range of 1–6. The forward reaction
was a function of initial glucose concentration but not the reverse reaction. It was concluded that the reaction kinetics
and equilibrium concentrations of the glycosylamines were pH-dependent and also a function of the acyclic content of the reacting
glucose isomer. 相似文献
2.
G. R. Davidson B. Nurcombe G. E. Kearney K. Davis 《Culture, medicine and psychiatry》1978,2(4):359-372
Critical incidents adapted to presentation in picture form were used to investigate responses of Aboriginal adolescents from Elcho Island mission in the Northern Territory of Australia in conflict situations arising from culture contact. These Aboriginal youths are part of a complex environment where choice behaviour is mediated by specific and broader situational characteristics of the social environment. Results showed a relationship between conflict responses and orientation to traditional values and skills, but no apparent relationship between conflict responses and modern value orientation or psychopathology variables. Adolescents who attended high school in Darwin were seen as more mission and academically oriented than locally educated youth. Contrary to expected patterns, males appeared to be less involved in both mission and traditional activities and more restricted by traditional social expectations than were females. 相似文献
3.
Steven I. Higgins Robert B. O’Hara Olga Bykova Michael D. Cramer Isabelle Chuine Eva‐Maria Gerstner Thomas Hickler Xavier Morin Michael R. Kearney Guy F. Midgley Simon Scheiter 《Journal of Biogeography》2012,39(12):2132-2145
Aim To develop a physiologically based model of the plant niche for use in species distribution modelling. Location Europe. Methods We link the Thornley transport resistance (TTR) model with functions which describe how the TTR’s model parameters are influenced by abiotic environmental factors. The TTR model considers how carbon and nutrient uptake, and the allocation of these assimilates, influence growth. We use indirect statistical methods to estimate the model parameters from a high resolution data set on tree distribution for 22 European tree species. Results We infer, from distribution data and abiotic forcing data, the physiological niche dimensions of 22 European tree species. We found that the model fits were reasonable (AUC: 0.79–0.964). The projected distributions were characterized by a false positive rate of 0.19 and a false negative rate 0.12. The fitted models are used to generate projections of the environmental factors that limit the range boundaries of the study species. Main conclusions We show that physiological models can be used to derive physiological niche dimensions from species distribution data. Future work should focus on including prior information on physiological rates into the parameter estimation process. Application of the TTR model to species distribution modelling suggests new avenues for establishing explicit links between distribution and physiology, and for generating hypotheses about how ecophysiological processes influence the distribution of plants. 相似文献
4.
Theofilos Poutahidis Sean M. Kearney Tatiana Levkovich Peimin Qi Bernard J. Varian Jessica R. Lakritz Yassin M. Ibrahim Antonis Chatzigiagkos Eric J. Alm Susan E. Erdman 《PloS one》2013,8(10)
Wound healing capability is inextricably linked with diverse aspects of physical fitness ranging from recovery after minor injuries and surgery to diabetes and some types of cancer. Impact of the microbiome upon the mammalian wound healing process is poorly understood. We discover that supplementing the gut microbiome with lactic acid microbes in drinking water accelerates the wound-healing process to occur in half the time required for matched control animals. Further, we find that Lactobacillus reuteri enhances wound-healing properties through up-regulation of the neuropeptide hormone oxytocin, a factor integral in social bonding and reproduction, by a vagus nerve-mediated pathway. Bacteria-triggered oxytocin serves to activate host CD4+Foxp3+CD25+ immune T regulatory cells conveying transplantable wound healing capacity to naive Rag2-deficient animals. This study determined oxytocin to be a novel component of a multi-directional gut microbe-brain-immune axis, with wound-healing capability as a previously unrecognized output of this axis. We also provide experimental evidence to support long-standing medical traditions associating diet, social practices, and the immune system with efficient recovery after injury, sustained good health, and longevity. 相似文献
5.
6.
G Cecchini M Perl J Lipsick T P Singer E B Kearney 《The Journal of biological chemistry》1979,254(15):7295-7301
Riboflavine uptake and membrane-associated riboflavin-binding activity has been investigated in Bacillus subtilis. Riboflavin uptake proceeds via a system whose general properties are indicative of a carrier-mediated process: it is inhibited by substrate analogues, exhibits saturation kinetics, and is temperature-dependent. The organism concentrates riboflavin primarily as the phosphorylated cofactors FMN and FAD. Energy is required for uptake but whether the energy demand is required for both uptake and phosphorylation or only for the phosphorylation step is not known. Membrane-associated binding activity for riboflavin has also been demonstrated in membrane vesicles prepared from B. subtilis, and the binding component can be "solubilized" with Triton X-100. Evidence supporting the function of the binding component in riboflavin uptake by the intact cells includes the following. (i) Riboflavin analogues inhibit binding and uptake to nearly the same extent and with similar specificity of action. (ii) The KD for riboflavin-binding and the Km for uptake are in the same range. Similarly the Ki determined for the inhibitory analogue 5-deazariboflavin in the uptake assay and the KD for its interaction with the riboflavin-binding component of membrane vesicles are in the same range. (iii) Uptake in cells and binding in vesicles vary in the same direction with differences in growth conditions. 相似文献
7.
Pre-B cells: bone marrow persistence in anti-mu-suppressed mice, conversion to B lymphocytes, and recovery after destruction by cyclophosphamide. 总被引:17,自引:0,他引:17
P D Burrows J F Kearney A R Lawton M D Cooper 《Journal of immunology (Baltimore, Md. : 1950)》1978,120(5):1526-1531
Chronic treatment of mice from birth with anti-mu antibodies aborts development of B lymphocytes and plasma cells. In these studies we show that bone marrow from anti-mu-treated mice contains a population of cells with cytoplasmic IgM, but which lack detectable cell-surface IgM. These cells are analogous to pre-B cells, defined in ontogenetic studies as the immediate precursors of B lymphocytes. Pre-B cells from bone marrow of anti-mu treated mice retain their functional integrity, as evidenced by their ability to give rise to sIgM+, LPS-responsive lymphocytes in culture. We also show that cyclophosphamide treatment destroys pre-B cells and that recovery of pre-B cells in bone marrow precedes the regeneration of sIgM+ B lymphocytes. Generation of B lymphocytes in adult mice apparently occurs exclusively in the bone marrow because induction of extramedullary hemopoiesis in spleen was not accompanied by the appearance of pre-B cells in that organ. 相似文献
8.
Extensively or completely activated preparations of beef heart succinate dehydrogenase have been investigated by electron paramagnetic resonance (EPR) techniques at 6 to 97 K. Reductive titrations with dithionite and rapid kinetic studies were performed with various types of soluble and membrane-bound preparations of the enzyme. The following components were detected and their behavior analyzed: a free radical, presumably arising from the covalently bound flavin on reduction, two iron-sulfur centers of the ferredoxin type, the signals of which appear on reduction, and a highpotential iron-sulfur component, detectable in the oxidized state. The high-potential component was only detected in complex II and inner-membrane preparations. This component and one of the ferredoxin-type centers were present in amounts close to stoichiometric with the flavin and were reduced by substrate. The other ferredoxin-type center was present in amounts between 0.1 and 0.5 times that of the flavin and was reduced only by dithionite. Of the components reduced by succinate, however, only a fraction (up to 50% of the high-potential iron-sulfur center and 40-60% of the ferredoxin-type iron-sulfur center) was reduced within the turnover time of the enzymes; In complex II not more than about 10% of the flavin appeared in the semiquinone form at any time. Soluble, purified preparations behaved similarly except that the high-potential component was nearly or completely absent and extensive accumulation of the free radical occurred (up to 70 to 80% of the flavin) in titration and kinetic experiments. No significant difference was observed between the rates of semiquinone formation and the reduction of the ferredoxin-type or high-potential centers by the substrate. Also no qualitative differences in the properties studied in this work became apparent between prepatations containing 4 or 8 iron atoms, respectively. 相似文献
9.
Elmén J Lindow M Silahtaroglu A Bak M Christensen M Lind-Thomsen A Hedtjärn M Hansen JB Hansen HF Straarup EM McCullagh K Kearney P Kauppinen S 《Nucleic acids research》2008,36(4):1153-1162
MicroRNA-122 (miR-122) is an abundant liver-specific miRNA, implicated in fatty acid and cholesterol metabolism as well as hepatitis C viral replication. Here, we report that a systemically administered 16-nt, unconjugated LNA (locked nucleic acid)-antimiR oligonucleotide complementary to the 5′ end of miR-122 leads to specific, dose-dependent silencing of miR-122 and shows no hepatotoxicity in mice. Antagonism of miR-122 is due to formation of stable heteroduplexes between the LNA-antimiR and miR-122 as detected by northern analysis. Fluorescence in situ hybridization demonstrated uptake of the LNA-antimiR in mouse liver cells, which was accompanied by markedly reduced hybridization signals for mature miR-122 in treated mice. Functional antagonism of miR-122 was inferred from a low cholesterol phenotype and de-repression within 24 h of 199 liver mRNAs showing significant enrichment for miR-122 seed matches in their 3′ UTRs. Expression profiling extended to 3 weeks after the last LNA-antimiR dose revealed that most of the changes in liver gene expression were normalized to saline control levels coinciding with normalized miR-122 and plasma cholesterol levels. Combined, these data suggest that miRNA antagonists comprised of LNA are valuable tools for identifying miRNA targets in vivo and for studying the biological role of miRNAs and miRNA-associated gene-regulatory networks in a physiological context. 相似文献
10.